CHAPTER II 



SICK SOILS NOT INFLXJENCED BY PABASITES 



We have seai that a normal and healthy soil is 

 one in which the beneficial soil flora is at its mayimnrn 

 of normal activity, making the food of the plant 

 assimilable. We have to discuss the abnormal or 

 sick soils now. In this dass we include those which 

 are^ther physically or chanically so constituted as 

 to have a detrimental effect on the activity of the 

 soil flora; and those which are overnm with organ- 

 isms directly parasitic on the plants grown in that 

 soil. There are five classes to be considered in the 

 first division. 



I. Denitrified Soils 



This detrimental condition in the soil is brought 

 about by a group of undesirable organisms, some 

 of which are Bacillus ramosus, B. pestifer, B. 

 mycoides, B. subtilis, B. mesentericiis vulgatus. 

 In C3iapter I we have seen that the nitrifying 

 bacteria oxidize the nitrogen and make it avail- 

 able for plants. In denitrification, the harmful 

 bacteria tend to reconvert the available nitrogen 

 into a non-available form, or else to liberate it into 

 the air, wh^e it may be considered as lost so 



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